Quantitative volumetric studies of brain morphological changes between childhood, adolescence, and you adulthood have yielded interesting results. Past neurodevelopmental studies have, however, been limited by the technology available for magnetic resonance image (MRI) acquisition, image analysis, and ultimately computering power to best exploit imaging data. The methods proposed for this study of normal brain maturation will include very high resolution structural images, tissue segmentation, brain surface renderings for aid in detailed cortical anatomical segmentation, and surface and volume (voxel based) modeling spatial localization techniques. With these relatively sophisticated methods, questions abut the etiology of maturational changes in the brain (e.g., myelination vs. Synaptic pruning) may be further examined Perhaps more importantly, assessing the spatial anatomical location of these maturational changes will be possible. Specific Aims a) To spatially localize structural maturational changes in the developing human brain b) Quantify the statistical significance of localized changes in hypothesized regions of greatest change relative to regions predicted to show little age-related structural change. Williams syndrome is a rare metabolic disorder labeled in 1961 by the British cardiologist J.C. P. Williams. who described a syndrome which includes a specific heart defect. mental retardation, and a peculiar facial appearance. Williams subjects also exhibit a unique fractionation of higher cortical functioning. specifically. selective preservation of complex syntax in the face of marked and severe cognitive deficits. While it is widely known that specific language deficits can exist without any accompanying cognitive deficit, the opposite pattern in which linguistic abilities are spared despite overall cognitive deficits is rare. It seems likely that the marked and specific deficits in behavioral development, and resultant neuropsychological profile in Williams patients result from unique patterns of aberrant brain development. 1. To understand the brain morphometric differences between Williams Syndrome and developmentally normal children using a high resolution imaging protocol. 2). Use morphometric findings to analyze factors which may account for the distinctive behavioral profiles found in this population.